The authors present their experience of late prosthetic thrombosis in which they performed a local thrombolysis as the first approach, aiming not only to cure the acute obstruction but also to get more information about the most appropriate therapeutic tactic to be used.The therapeutic protocol consisted of: (1) urokinase: 200,000 IU in 15-20 minutes, and after this, 75,000 IU/hour for a maximum of 72 hours, always through the arterial catheter; (2) heparin: 5,000 IU before the thrombolytic treatment is started and then maintenance of a sodium heparin infusion with a pump, the activated partial thromboplastin time being taken at double the initial value.